Water Testing 101

Hi Permies-- Apologies if I missed this elsewhere-- part time lurker, first time poster, feel free to redirect me.

I have this bucket list item to catch and/or farm my weight in fish (only 115 more lbs to go!)

Looking to convert a 60-ish gallon koi pond into the foundation for an aquaponics system and stock with tilapia or something similarly newbie friendly and edible.

Everything I've read on aquaponics so far emphasizes testing water quality, but I haven't found any that go into more detail.

So now I'm holding an intimidating box that says it will test pH, Ammonia, Nitrite, Nitrate levels and another for colorimetric and titration. This would be to test municipal tap water that has stood a couple days to dechlorinate, or perhaps been helped along with a crushed vitamin C tablet if we're in a hurry. The water hasn't killed the duckweed yet... although duckweed probably got its name for being pretty hardy. Is this sufficient testing equipment? Overkill?

Anyone have any go-to resource suggestions for how to test fish water and what ranges the values should fall into?
Which ones are most critical to pay attention to?
Can anyone share how often you actually find yourself testing your water and around what events?

Thanks for your help!

Hi Chris,

The 4 in 1 box you are holding is a great start. Follow the directions to the "t" and you will have good results. It is good to test your water right at start to get a baseline of what your conditions are. It would be a good idea to test the water with the duckweed and the tap water. Letting the water dechlorinate is a good practice.

During system startup you will need to test more often. Once a week while it is cycling will give you a good look at what is happening. And cycling can take anywhere from 4-6 weeks Testing before adding fish, starting plants for the first time, etc. are all good references, after things are going and stable testing can be done much less frequently.

Post your results here and lets see what you are starting with.

Pura Vida

Chlorine: Null

**4-box** turned out to be a 5-box with a "high" pH test as well

pH: 8.4
Ammonia: 0.25 ppm
Nitrite: 0 ppm
Nitrate 0 ppm

So the pH is the only thing that looked like it was on the extreme side.
Someone on a random blog mentioned amending high pH with vinegar, does that work?

Youtube of the setup. Supposed to have 12 Hawaiian Gold coming sometime this week.

Your numbers aren't crazy. High range Ph will "lock out" the plants ability to uptake nutrients, the effect on the fish is negligible at this time.
Low ammonia is leading to low levels of nitrite & nitrate... Amending Ph with vinegar can work. It is an organic source so its ability for long term buffering degrades over time. Phosphoric acid will give you a better buffering ability and add P to your system which will benefit the plants. I would recommend making sure that anything you add is food quality/ purity.

It would be awesome to add some biology to the water. This will get things cycling faster. Adding a little ammonia and worm castings would be a good idea, a good hand full in a paint strainer bag works great. I can give you some more info on the biology stuff if you are interested. High Ph can be beneficial in the cycling phase.


A few q's for you...
How big are these new fish?
I am asking because your system will need to cycle which will help drop Ph and also get the nitrification process going. Too many fish, that are large will overwhelm your system given the small ratio of grow space to potential fish density.
Do you have any kind of filter system?
Is there an air pump or are the bubbles under the watering can coming from the water draining back down into the tank?

You have a great start here. Good luck

Great tips--

You were right about the degrading buffering ability of vinegar-- I managed to bring it down to 8.0 before the fish came, but when I retested yesterday, it had bounced back up to 8.3 and I am out of vinegar. Will add food grade Phosphoric acid to the shopping list.

Truth on adding biology! Since the fish are tiny (1-1.5"), they aren't keeping up with the vigor of the duckweed, which I guess is a start. I read that taro is water loving and picked up a stalk at the grocery store and dropped it in the watering can just to see what would happen... Nothing so far. A "super dwarf cavendish musa" (Musa acuminata) is also on its way. They say the banana tree should stay sub-4 feet. It may not fit in the watering pot, but it can probably soak its roots in a similarly diametered planter, at least until the arrangement becomes too precarious. I wonder if when its canopy comes in it might help stem some of the evaporation off the pond? In semi-arid socal, it seems the pond level can drop as much as an inch in a day. How do other folks combat evaporation? There would be less surface area on a 55 gallon plastic barrel but then would I need to worry more about aeration and limit the plant options?

Didn't realize adding ammonia might actually be beneficial-- I have an abundance of worm castings and can probably macgyver a strainer bag equivalent in a couple mins


Answers to your q's--

How big are these new fish?
--fingerlings1-1.5". There were 14 originally, it is tough to get them to hold still long enough to count past 10 at the minute. They don't seem too densely stocked for their current size.

Do you have any kind of filter system?
--not at the minute, potentially in a future state. We found some rad videos of folks running hydroponic sluices-- PVC tubes they had hole sawed grow baskets into. They had to pump the water to the top, but then it could gravity feed its way through 90 feet of PVC from there. A little worried about fully integrating this sort of filtration with the fish pond until we know what we're doing. We may try changing out some of their water and feeding the dirty water through this sort of setup to see how it goes. Is there a more elegant way to filter? The pond already feels a bit like it is on life support with its air pump and heater plugged in.

Is there an air pump or are the bubbles under the watering can coming from the water draining back down into the tank?
--that bubbling is an air pump we anchored under an overturned clay pot that the watering can is sitting on. We didn't have aquarium-specific tubing or air stones, so it is an old drip irrigation hose free flowing.''

Thanks again for your help!